The Relation between Rheumatoid Arthritis and Diabetes Mellitus: a Systematic Review and Meta-Analysis

Objectives This systematic review and meta-analysis was conducted to investigate the relationship between rheumatoid arthritis (RA) and the incidence of diabetes mellitus (DM). Methods A comprehensive search was conducted up to March 10, 2020 in Medline (via Ovid), Embase (via Ovid) and Web of science core collection to identify cohort studies comparing the risk of DM incidence in people with RA with the general population. The I2 statistic was used to test heterogeneity. Pooled relative risks (RR) were calculated using random-effects models. Publication bias was assessed using funnel plot, Egger’s test and Begg’s test. Results The initial search provided 3,669 articles. Of those, five journal articles and two conference abstracts comprising 1,629,854 participants were included in this study. The funnel plot showed potential publication bias, proven by Egger’s test (-3.15, P<0.01), but not Begg’s test (-0.05, P=1.00). Heterogeneity was observed in I2 test (I2=96%, P<0.01). We found that RA was associated with a higher risk of DM incidence (pooled RR 1.23; 95% CI 1.07-1.40). Exploration of potential sources of heterogeneity found significant heterogeneity among different countries or regions (P=0.002), but heterogeneity was not significant for differing study designs (P=0.30). Sensitivity analyses confirmed that the association between rheumatoid arthritis and diabetes mellitus incidence was robust. Conclusion RA is associated with an increased risk of diabetes incidence. This finding supports the notion that inflammatory pathways are involved in the pathogenesis of diabetes. More intensive intervention to target diabetes risk factors should be considered in people with RA.